1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_CLASSFILE_STRINGTABLE_HPP
26 #define SHARE_VM_CLASSFILE_STRINGTABLE_HPP
27
28 #include "memory/allocation.inline.hpp"
29 #include "utilities/hashtable.hpp"
30
31 template <class T, class N> class CompactHashtable;
32 class CompactHashtableWriter;
33 class FileMapInfo;
34
35 class StringTable : public RehashableHashtable<oop, mtSymbol> {
36 friend class VMStructs;
37 friend class Symbol;
38
39 private:
40 // The string table
41 static StringTable* _the_table;
42
43 // Shared string table
44 static CompactHashtable<oop, char> _shared_table;
45 static bool _ignore_shared_strings;
46
47 // Set if one bucket is out of balance due to hash algorithm deficiency
48 static bool _needs_rehashing;
49
50 // Claimed high water mark for parallel chunked scanning
51 static volatile int _parallel_claimed_idx;
52
53 static oop intern(Handle string_or_null, jchar* chars, int length, TRAPS);
54 oop basic_add(int index, Handle string_or_null, jchar* name, int len,
55 unsigned int hashValue, TRAPS);
56
57 oop lookup_in_main_table(int index, jchar* chars, int length, unsigned int hashValue);
58 static oop lookup_shared(jchar* name, int len);
59
60 // Apply the give oop closure to the entries to the buckets
61 // in the range [start_idx, end_idx).
62 static void buckets_oops_do(OopClosure* f, int start_idx, int end_idx);
63 // Unlink or apply the give oop closure to the entries to the buckets
64 // in the range [start_idx, end_idx).
65 static void buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, int* processed, int* removed);
66
67 StringTable() : RehashableHashtable<oop, mtSymbol>((int)StringTableSize,
68 sizeof (HashtableEntry<oop, mtSymbol>)) {}
69
70 StringTable(HashtableBucket<mtSymbol>* t, int number_of_entries)
71 : RehashableHashtable<oop, mtSymbol>((int)StringTableSize, sizeof (HashtableEntry<oop, mtSymbol>), t,
72 number_of_entries) {}
73 public:
74 // The string table
75 static StringTable* the_table() { return _the_table; }
76
77 // Size of one bucket in the string table. Used when checking for rollover.
78 static uint bucket_size() { return sizeof(HashtableBucket<mtSymbol>); }
79
80 static void create_table() {
81 assert(_the_table == NULL, "One string table allowed.");
82 _the_table = new StringTable();
83 }
84
85 // GC support
86 // Delete pointers to otherwise-unreachable objects.
87 static void unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f) {
88 int processed = 0;
89 int removed = 0;
90 unlink_or_oops_do(cl, f, &processed, &removed);
91 }
92 static void unlink(BoolObjectClosure* cl) {
93 int processed = 0;
94 int removed = 0;
95 unlink_or_oops_do(cl, NULL, &processed, &removed);
96 }
97 static void unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f, int* processed, int* removed);
98 static void unlink(BoolObjectClosure* cl, int* processed, int* removed) {
99 unlink_or_oops_do(cl, NULL, processed, removed);
100 }
101 // Serially invoke "f->do_oop" on the locations of all oops in the table.
102 static void oops_do(OopClosure* f);
103
104 // Possibly parallel versions of the above
105 static void possibly_parallel_unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f, int* processed, int* removed);
106 static void possibly_parallel_unlink(BoolObjectClosure* cl, int* processed, int* removed) {
107 possibly_parallel_unlink_or_oops_do(cl, NULL, processed, removed);
108 }
109 static void possibly_parallel_oops_do(OopClosure* f);
110
111 // Hashing algorithm, used as the hash value used by the
112 // StringTable for bucket selection and comparison (stored in the
113 // HashtableEntry structures). This is used in the String.intern() method.
114 template<typename T> static unsigned int hash_string(const T* s, int len);
115
116 // Internal test.
117 static void test_alt_hash() PRODUCT_RETURN;
118
119 // Probing
120 static oop lookup(Symbol* symbol);
121 static oop lookup(jchar* chars, int length);
122
123 // Interning
124 static oop intern(Symbol* symbol, TRAPS);
125 static oop intern(oop string, TRAPS);
126 static oop intern(const char *utf8_string, TRAPS);
127
128 // Debugging
129 static void verify();
130 static void dump(outputStream* st, bool verbose=false);
131
132 enum VerifyMesgModes {
133 _verify_quietly = 0,
134 _verify_with_mesgs = 1
135 };
136
137 enum VerifyRetTypes {
138 _verify_pass = 0,
139 _verify_fail_continue = 1,
140 _verify_fail_done = 2
141 };
142
143 static VerifyRetTypes compare_entries(int bkt1, int e_cnt1,
144 HashtableEntry<oop, mtSymbol>* e_ptr1,
145 int bkt2, int e_cnt2,
146 HashtableEntry<oop, mtSymbol>* e_ptr2);
147 static VerifyRetTypes verify_entry(int bkt, int e_cnt,
148 HashtableEntry<oop, mtSymbol>* e_ptr,
149 VerifyMesgModes mesg_mode);
150 static int verify_and_compare_entries();
151
152 // Sharing
153 static void ignore_shared_strings(bool v) { _ignore_shared_strings = v; }
154 static bool shared_string_ignored() { return _ignore_shared_strings; }
155 static void shared_oops_do(OopClosure* f);
156 static bool copy_shared_string(GrowableArray<MemRegion> *string_space,
157 CompactHashtableWriter* ch_table);
158 static bool copy_compact_table(char** top, char* end, GrowableArray<MemRegion> *string_space,
159 size_t* space_size);
160 static const char* init_shared_table(FileMapInfo *mapinfo, char* buffer);
161 static void reverse() {
162 the_table()->Hashtable<oop, mtSymbol>::reverse();
163 }
164
165 // Rehash the symbol table if it gets out of balance
166 static void rehash_table();
167 static bool needs_rehashing() { return _needs_rehashing; }
168
169 // Parallel chunked scanning
170 static void clear_parallel_claimed_index() { _parallel_claimed_idx = 0; }
171 static int parallel_claimed_index() { return _parallel_claimed_idx; }
172 };
173 #endif // SHARE_VM_CLASSFILE_STRINGTABLE_HPP